Nigeria is today faced with a lot of problems that threaten its prosperity as a nation. Virtually all sectors of the country have one or two challenges that need attention. For example, the agriculture sector – the one whose success may result in the success of the other sectors – is laden with many problems that pose a greater challenge to the populace.
One way to assess the situation is to check the production volume of food grown domestically by local farmers. Although there has been an observed facelift in the agriculture sector of the country, especially under the present administration; the production is still not satisfying the orgy of the growing population of the country.
The growth of food production is dismally low (growing at the rate of between 1% and 1.5% per annum); the rate of population growth is 2.8% while food demand is put at the rate of 3.5%.
What these figures embody is: governments of different countries, especially third-world countries, must brace to the challenges and find lasting solutions to liberate their population from the shackles of hunger.
And the best way to address the situation is to invest in agriculture; accord priority to it, make it more attractive to the youth and all farming population and provide necessary assistance to them to enable them to produce optimally.
In Nigeria, arable land (% of land area) was reported at 37.33 % in 2018, according to the World Bank collection of development indicators, compiled from officially recognized sources, and out of this, between 4.0 and 4.5million hectares (approximately 5% of the land) is judged suitable for irrigation activities.
Going by the current realities of the country, the best alternative to filling the demand gap in the food supply is to revamp irrigation programmes so that there would be all-year-round production of food. The predominant rainfed agriculture cannot sustain the teeming population.
Dry season farming is the system of farming that uses and relies on irrigation.
Irrigation is the artificial application of water to crops to supply moisture essential for the growth and development of crops. This practice allows farmers to produce crops all year round thereby increasing the production volume of food in the country and consequently contributing to the attainment of food sufficiency.
Research shows that about 60-90% of a physiologically active plant is water, which is required by plants for photosynthesis, digestion, growth, transport of minerals and photosynthates, structural support and transpiration.
Water is used primarily by plants for transpiration. Because of this reason, off-season farming is only possible when there is water that would be supplied to the crops throughout their growth stages.
Objectives of irrigation
- To supply water to the crops.
- To provide crop insurance against short duration drought.
- To moisten the soil and make the environment more favourable for plant growth.
- To facilitate the activation and functioning of some microorganisms.
- To boost food production and make farming an all-year-round business.
Importance of irrigation
- It ensures all-year-round production of crops.
- It provides employment opportunities for people during the dry season.
Classification of crops based on their water requirement
Crops vary in their requirement for or consumption of water. Based on this, crops can be grouped into three different groups; namely:
Hydrophytes: crops that require a lot of water for their growth and development. Examples of cultivated hydrophytic crops include paddy rice, sugarcane, banana, etc.
Mesophytes: these are crops that require moderate water for their growth and development. Their water requirement is between that of hydrophytes and xerophytes. Examples of such crops include maize, groundnut, soybeans, sorghum, tomato, etc.
Xerophytes: these are crops that require little water for their growth and development. They are somewhat drought tolerant and can survive in the presence of mist and dew. Examples include cowpea, date palm, millet, etc.
Forms of irrigation
Two different forms of irrigation exist. They are gravitational and pressurized pumps. In the former form, the water flows naturally or is guided to the farm from the source without any use of force.
An example of irrigation that uses this form is surface irrigation; a gravity-fed irrigation system that supplies water to the soil surface using gravity.
The pressurised pump, on the other hand, uses artificial force to direct or pump water to the field. Examples of irrigation types using this form are subsurface, sprinkler and drip irrigation; which require a pumping machine.
Crops to grow under irrigation
Different crops can be grown under an irrigation farming system, although success could, to a large extent, be a function of good management practice employed by the farmer.
FAO-Aquastat 2016 (Aquastat is the FAO global information system on water resources and agricultural water management) explained that the dry northern savannah is appropriate for sorghum, millet, maize, groundnut and cotton while cassava, yam, plantain, maize and sorghum can successfully be grown in the Middle belt. Different types of vegetables, garden crops and other crops such as onions, carrots, tomato, pepper, cucumber, okra, eggplant, garden egg, melon, spinach, sweet potato, wheat, maize, cowpea, citrus, cocoa, etc, can also be grown under irrigation system.
There are three irrigation schemes in Nigeria; namely:
- Government-executed schemes
- Farmer-owned scheme
- Floodplain scheme, also known as FADAMA Irrigation Scheme.
The government irrigation schemes are not enough to provide the needed volume of production that would put the country on the trajectory of food sufficiency. Coupled with this is the government’s poor attitude to harnessing the irrigation potential in the country.
Yahaya (2002) noted that only 45% of the total irrigation potential of 2.0 million hectares is under irrigation. He pointed out that most of the government-owned dams are either under-utilised for irrigation or abandoned.
It is, therefore, important that farmers should consider going into farmer-owned dry season farming since the Fadama and other government schemes are either abandoned or concentrated in a few areas to benefit only a small number of farmers.
Factors to consider in irrigation
For profitable dry season farming, farmers must consider certain factors when irrigating their crops. Some of these factors to be considered include:
- Climatic factors
- Crop type
- Soil type
Factors such as temperature, wind, etc should be considered when irrigating farmland.
Farmers should try to find answers to the following questions before irrigating their crops:
What type of crop am I growing? Is it hydrophytic or mesophytic? Finding the answer to this is important as crops vary in their requirement for water. Over irrigation can lead to water loss, leaching of nutrients, etc. Are the crops leafy? Are they narrow-leaved?
What type of soil is on the farmer’s field? Sandy, clay, clay-loam? Of course, with clay or clay-loam, farmers may be required to supply more water than they would with sandy soil; this is because of the varying water holding capacity of the soils.
The decision as to when to irrigate and how much water to apply per irrigation is critical to the success of dry-season farming as proper scheduling ensures efficient use of water, energy and other production inputs such as fertilizers.
How To Determine Irrigation Scheduling
There are methods used in determining irrigation scheduling. These methods are:
- Plant indicator
- Soil indicator
- Water budget techniques
The plant indicators method involves assessing the plant through visual appearance. Is the plant wilting, is the plant moisture-stressed? Has the colour of the plant changed? (Although this could be due to so many reasons as a deficiency in certain nutrients etc.)
Soil indicators involve the appearance and feel method where a farmer takes a sample of the soil and feels it to tentatively ascertain its moisture content.
Water budgeting techniques involves using some equation to track soil moisture levels and other parameters to determine the time and volume of irrigation.
Agronomic practices of irrigated crops
These are management practices given to crops before, during and after planting to make them thrive. These include land preparation, planting, weeding, mulching, supplying, thinning, fertilisation, pesticide/insecticide application, etc. All these must be done as and when due.
Guidelines for improving irrigation practices
- Check the soil moisture in the root zone before irrigating. Observe the physical appearance of the plant and the soil. This will help you estimate the amount of water required to bring the soil to field capacity.
- Determine the depth of water applied to the field during irrigation to know whether the water covers the rooting depth.
- Determine whether the water applied corresponds with the amount needed by the crop to prevent over and under-utilisation of water, which will cause problems.
- Check whether the intake opportunity time (the interval during which water will infiltrate at a specified location) is about the same time throughout the field. Knowing this will help you know the area that needs much or less water to bring the soil to field capacity.
- Observe the amount of irrigation water flowing out of the field after the saturation of the soil. This will help avoid run-off and wastage.
- A review of the evaluation of irrigation practice in Nigeria: Past, present and prospects by Bashir Adelodun and Kyung-Sook Choi
- Principles of Irrigation and Drainage; a reading material of the National Open University of Nigeria.
Rilwan Muhammad can be reached via firstname.lastname@example.org at 07061124918